table locking

[Andy Nicastro]

Hi,

I want to develop a multi-user application using mod_perl 2 with MySQL 5.0.

I have been experimenting via the comaand line mysql interface with row level locking.

If in one window I do
SELECT * FROM IMAGES WHERE IMAGE_ID = 135 FOR UPDATE;

and then in a second command window I do
UPDATE IMAGES SET IMAGE_LOCATION = 'XXX' WHERE IMAGE_ID=135;

MySQL allows the second update to execute and updates the record.
I had expected the seond statement to return an error indicating that the row was locked by another user.

What am I doing wrong to achieve the lock?

Thanks for your help.
Andy